Abstract
Mechanisms of chloride (Cl-) exclusion in rootstocks of grapevine (Vitis spp.) were studied using a strong Cl--excluding rootstock (140 Ruggeri) and a poor Cl--excluding rootstock (K51-40). Xylem Cl- concentration in potted whole grapevines of 140 Ruggeri treated with 50 mM Cl- was 6.8-fold lower than that in K51-40. Five-fold lower total shoot Cl-in salt-treated 140 Ruggeri grapevines relative to that in K51-40 after 50 days, when shoots were of similar biomass, was unrelated to water use. Unidirectional influx of Cl-36(-) into excised roots (up to 30 min), and uptake of Cl-36(-) in roots of intact rooted-leaves (up to 180 min) in 10 mM Cl- was similar between the genotypes. However, net accumulation of Cl- by excised roots of K51-40 up to 180 min in 10 mM Cl- was significantly higher than that of 140 Ruggeri. Intact rooted-leaves of 140 Ruggeri in 10 mM Cl- accumulated higher Cl- concentrations in roots, and had a lower percentage of total plant Cl-36(-) accumulation in the shoot (petiole plus lamina) than those of K51-40. The greater Cl- exclusion capacity of 140 Ruggeri appears to be associated with restricted entry of Cl- to xylem and lower root to shoot Cl- transport.